Alton, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

752
FXUS66 KEKA 122022
AFDEKA

AREA FORECAST DISCUSSION
National Weather Service Eureka CA
122 PM PDT Sun Jul 12 2026

.KEY MESSAGES...

* Interior Heat: An upper-level ridge has moved westward causing
  temperatures to rise above normal across inland valleys into early
  next week.

* Slight Threat for Isolated showers/thunderstorms. A 10 to 20%
  chance for thunderstorms Monday and Tuesday. The highest chances
  are in Trinity County on Tuesday afternoon.

* Coastal flooding: Minor coastal flooding around Humboldt Bay
  possible at the evening high tide tonight through Tuesday night.


&&

.SYNOPSIS...Hot temperatures return to much of the interior today.
Monsoonal moisture will bring cloud cover and moisture Monday and
Tuesday. Isolated thunderstorms or showers are possible Monday and
Tuesday in the interior.


&&

.DISCUSSION...An upper level trough in British Columbia continues to
inch eastward while an upper ridge over the Southwest US continues
to expand westward. This ridge will bring above normal temperatures
to the interior with 90s likely for most valleys and the warmest
areas possible exceeding 100. Monsoonal moisture from the south has
started to stream over the area in the form of high clouds.  So far,
none of these have resulted in showers that reached the ground. This
may change overnight as additional moisture streams in early Monday
morning. CAMs are showing a higher potential for a few rain showers,
especially in Mendocino, Lake, and Trinity Counties. Instability is
limited, but an isolated thunderstorms is possible with an
especially strong shower. Dry surface conditions will likely prevent
most precipitation from reaching the ground. This pattern continues
Monday afternoon and overnight through Tuesday morning. Instability
still remains limited, but a stray thunderstorm cannot be ruled out.
Thunder chances increase Tuesday afternoon with added surface
heating. The highest chances are in Trinity County with up to 20%
chance for thunderstorms, though CAMs within range show convection
both farther west and farther east.

High temperatures are forecast to remain in the 90s for most
interior valleys with the warmest areas exceeding 100 early next
week. Additional cloud cover early next week may nudge these
forecasted temperatures down a few degrees. HeatRisk remains minor
to locally moderate. Coastal areas remain in the high 50s to mid 60s
with stratus forming overnight and partially clearing by the
afternoon. Drier air returns midweek as the Pacific Northwest trough
moves southwestward. A deeper marine layer will likely bring
interior temperatures down by a few degrees, while bringing more
widespread, and possibly persistent, coastal stratus. High pressure
returns late next week, returning warmer interior temperatures. /JB


&&

.AVIATION...(18Z TAFs)...Coastal stratus remains off the Humboldt
and Del Norte coasts early this afternoon, but has retreated
offshore. Some periodic stratus impacts are possible into the
afternoon as the stratus disperses. Breezy northerly winds are
likely across the area in the afternoon, especially along the coast.
Stratus is likely to return again tonight with a southerly return
flow likely to advect stratus northward from Humboldt Bay to CEC.
LIFR to IFR ceiling impacts are likely should stratus develop with
visibility reductions possible around sunrise. Stratus will likely
lift and scatter shortly after sunrise. VFR conditions are likely
for the interior areas for the next 24 hours. There is a small
chance for thunderstorms (10%) for much of the interior area
overnight and into Monday. /JB


&&

.MARINE...Northerly winds peak this evening with localized gale
force gusts in the lee of Cape Mendocino and sustained winds of 20-
25 kts in the outer waters. Nearshore winds will be much lighter at
10-20 kts, but could still be breezy this afternoon. Northerly winds
ease somewhat Monday into Tuesday, but will remain strong in the lee
of Cape Mendocino. Strong winds and steep seas return mid to late
next week. Seas will be dominated by wind waves and a short period
northwest swell. Steep wind waves may propagate to the inner waters
even as winds remain milder. /JB


&&

.FIRE WEATHER...Monsoonal moisture has arrived to the area and will
peak Monday and Tuesday. There is high uncertainty if this will lead
to thunderstorms as instability is low, but with warm and dry low
levels, any thunder is likely to be dry. Some CAM runs are showing
some potential for convection starting early Monday morning and
afternoon and again Monday night into Tuesday morning. These pulses
will start in the south and move northward. Most models show this
feature, but instability is much weaker. Thus there are several
slight chance opportunities for a few isolated storms over the area.
The highest chance for thunderstorms remains on Tuesday afternoon
when the heating of the day increases thunderstorms chances to
around 10-20% in Trinity County and into the Yolla Bollys. This may
still nudge westward and southward, but is highly dependent on how
far east the moisture nudges. Some models do show moisture
completely to the east of the area, still, so confidence generally
remains low. /JB/RPA


&&

.COASTAL FLOODING...High astronomical tides may lead to minor
coastal flooding at the evening high tide each evening through
Tuesday evening. Minor flooding occurs when the North Spit tide
gauge reaches 8.8 ft MLLW. The astronomical tide is forecast to be
8.22 ft tonight, 8.32 ft Monday night, and 8.23 ft Tuesday night.
With an anomaly of 0.5-0.6 ft, the tide may exceed 8.8 ft, which
would could bring minor flooding impacts to King Salmon and Jackson
Ranch Road in the Arcata Bottoms. /JB


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...
     Coastal Flood Advisory from 9 PM this evening to midnight
     PDT tonight for CAZ103.

NORTHWEST CALIFORNIA COASTAL WATERS...
     Coastal Flood Advisory from 9 PM this evening to midnight
     PDT tonight for PZZ415.

     Small Craft Advisory until 9 PM PDT this evening for PZZ455.

     Small Craft Advisory until 11 PM PDT Monday for PZZ470.

     Small Craft Advisory until 3 AM PDT Wednesday for PZZ475.

&&

$$

NOTE: The full forecast discussion is now regularly issued between
10 am/pm and 1 pm/am. Additional updates will be issued as needed.

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https://www.weather.gov/images/eka/zonemap.png